KR100457986B1 - Apparatus for recording a digital information signal on a track on a record carrier and encoding means for encoding the digital information signal - Google Patents

Abstract

A switch 10 is provided to obtain a serial data stream of preamble signals and precoded data for writing to the track on the record carrier 20 when writing the preamble signal and nT precoded data. Several solutions are described to improve sink word detection during playback of recorded data. In one such solution, an nT precoder 6 'is provided, which includes signal combining means 32 and a delay means 30 for realizing the signal delay of nT. Also provided is switching means 10 having a first input (c) and a second input (a), an output (b), and a control signal input (24). The second input (a) of the switching means 10 is connected to the output of the signal combining means 32 and the output of the switching means is connected to the input of the nT delay means 30.

Description

Apparatus for recording a digital information signal on a track on a record carrier and encoding means for encoding the digital information signal

A device as defined in the opening paragraph is known from document D1 in EP-A 492,704, the list of relevant documents as seen at the end of this specification, in particular, see FIG. 12 of this document D1. Where n is equal to 2 in prior art devices.

Prior art devices may be digital information signals, i.e., digital video signals or digital audio signals, or may include both digital video signals and digital audio signals, or may record digital information signals, which may include digital data signals Record on oblique tracks on the carrier. The tracks are formed of a preamble track portion in which a preamble signal is recorded and a data track portion in which a subsequent channel signal is recorded. The channel signal recorded in the data track portion is a 2T precoded version of the data blocks (syncblocks) sequence, and each data block (sync block) contains a sync word followed by the number of bytes of information. The preamble signal is used for locking the internal oscillator of the playback apparatus with respect to the bit clock included in the preamble signal during playback. Next, the sync words of the data blocks (sync blocks) are detected, so that data information contained in the data blocks can be retrieved.

The present invention relates to an apparatus for recording a digital information signal on a track on a record carrier,

An input means for receiving a digital information signal,

- encoding means for encoding a digital information signal to obtain a channel signal, the encoding means comprising an nT precoder, where n is an integer n > = 1, T is a bit time of the digital information signal (bit time), the nT precoder comprises signal combining means and delay means for realizing a signal delay of nT,

- preamble signal generating means for generating a preamble signal,

Switching means for combining the preamble signal and the channel signal and having first and second input, output and control signal inputs, the first input of the switching means being connected to the output of the preamble signal generating means,

Timing means for timing the switching means so that the switching means supplies a channel-encoded block of digital information signal information following the preamble signal,

Recording means for recording a preamble signal and a channel-encoded block of information of the digital information signal in the track on the record carrier; and encoding means for encoding the digital information signal.

1 shows a device of the prior art;

2 is a diagram showing an embodiment of a 2T precoder;

Figures 3A-3C illustrate timing of some signals.

Figures 4A-4C illustrate a solution according to the invention applied to the device of Figure 1;

Figure 5 shows an embodiment of an apparatus according to the invention using a different solution.

Figures 6A-6C illustrate timing of several signals of the device of Figure 5;

7 is a view showing another embodiment of the apparatus.

Figures 8A-8C illustrate timing of some signals of the apparatus of Figure 7;

The present invention aims to improve sync word detection during subsequent playback of the information recorded on tracks. The device according to the invention is characterized in that the switching means forms an nT precoder part, the second input of the switching means is connected to the output of the signal combining means, and the output of the switching means is connected to the input of the nT delay means.

The present invention is based on the following recognition. The prior art apparatus generates a preamble signal defined by a write current pattern. The digital information signal is precoded using a 2T precoder to generate a write current to record the digital information signal on a record carrier. Changing the preamble signal to a 2T precoded digital information signal during recording results in an unknown two bits at the beginning of the reproduced digital information signal during reproduction. This is because the contents of the 2T delay means of the precoder when starting to precode the digital information signal are generally not the same as the last two bits of the preamble signal (write current signal). As a result, less than two bits can be used during playback for sync word detection, since the sync word is the first word in the precoded data stream immediately following the preamble signal.

According to the invention, the input of the delay means is connected to the output of the switching means, thereby receiving the preamble pattern before the switching means is switched to another position. The content of the nT delay means is now equal to the last n bits of the preamble signal and is thus the first n bits of the prescribed precoding information. This makes sinkword detection more reliable, because it allows the increased number of bits (n) to be used for sinkword detection. That is, the sync word detector can detect sync words of n bits or more.

Other solutions can be applied to prior art devices by advancing the moment of switch to another switch position by at least nT.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments illustrated in the accompanying drawings.

Figure 1 schematically shows only a relevant part of the prior art device. This device forms a record of the Partial Response Class IV (PRIV) system. To further illustrate the PRIV system, reference is made to document D2, EP-A 317,013, in the Related Documents List of the present disclosure. The input terminal 2 is connected to the input 4 of the 2T precoder 6 and the output 8 of the precoder is connected to the terminal 'a' of the controllable switch 10. There is provided a preamble signal generator 12 having an output connected to the terminal 'c' of the switch 10. The terminal 'b' is connected to the input 16 of the recording unit 18. A timing unit 22 is provided for generating timing signals for various elements of the apparatus. Figure 1 only shows the generation of a timing signal supplied to the control signal input 24 of the switch 10. [ The recording unit 18 is provided with at least one recording head for recording signals applied to the input 16 on the record carrier 20. [ 2T precoders are well known in the art. 2 shows one embodiment of a 2T precoder, which includes a signal combining unit 32 and a delay unit 30. [

The preamble signal generator 12 generates a preamble signal in the form of a write current pattern, which may include a sequence of codewords, as defined in document D1. A codeword is a binary sequence,

Or an inverse binary sequence. The preamble signal is defined as a write current pattern, and as a result, the sequence is supplied directly to the recording unit 18. That is, there is no precoding in the 2T precoder.

A digital information signal is supplied to the input terminal 2 and precoded in the precoder 6 to obtain a write current (channel signal) for writing a digital information signal on the record carrier 20. Document D1 describes a digital information signal in the form of a sequence of data blocks (sync blocks), and each data block (sync block) contains a sync word followed by the number of bytes of digital information. When recording digital information on a record carrier, a preamble signal is first recorded and then a sequence of precoded data blocks is recorded. Figure 3A shows the signal supplied to the input 16 of the recording unit 20, As a function. Under the influence of the timing signal (not shown) generated by the timing unit 22, the generator 12 starts generating a preamble signal at instant t = t ₀ . At this moment, the switch 10 is at (or is switched to) the position cb, so that the preamble signal is supplied to the recording unit 18 as the write current and written to the track. The generation of the preamble signal is terminated at instant t = t ₁ . Next, a source (not shown) begins to supply the digital information signal at the instant t = t ₁ , for example under the influence of the timing control signal (not shown) supplied by the timing unit 22 . The information signal is 2T precoded and supplied to the a- terminal of the switch 10. Further, under the influence of the timing control signal supplied to the switch 10 by the timing unit 22, the switch changes the switch position to the position ab, so that 2T precoded data is written to the recording unit < _{RTI ID} = (18). This is shown in Fig. 3A, which shows the serial data stream (write current) supplied to the recording unit 18. Fig. 3B shows the timing control signal supplied to the switch 10 by the timing unit 22. Fig. Before the instant t ₁ , the switch is in position cb, and after the instant t ₁ , the switch 10 is at position ab. As a result, the delay time information of the 2T delay unit 30 in the precoder 6 at t ₁ is not equal to the last two bits of the preamble signal. This eventually causes problems during playback.

FIG. 3C schematically shows the signal received at the time of reproduction. As can be seen from this figure, the first two bits b _i and b _{i + 1} in the reproduced data are unknown bits. If the first p bits are defined as a sync word, only p-2 bits can be used in the sync word detector to detect the sync word. This detection is less reliable when the sync word detector uses all the p bits for sync word detection.

Figures 4A-4C illustrate a first solution to this problem that may be applied to the apparatus of Figure 1. 4A shows the preamble signal generated by the generator 12 at time interval t ₀ , t ₁ and 2T precoding data supplied by the precoder 6 starting at instant t ₁ . 4B shows the timing signal supplied to the switch 10 by the timing unit 22. Fig. As can be seen in the figure, the switch 10 is switched to the position at the instant t ₁ I 2 ab bit period (T). This means that the last two bits of the preamble signal are not recorded on the record carrier 20. This is not a problem since the preamble signal is long enough to realize locking in of the internal oscillator of the reproducing apparatus with respect to the bit clock included in the preamplifier signal.

By switching the switch to the position t ₁ I 2-bit period, which means that the contents of the 2T delay unit 30 at moment t _1, the precoder 6 is equal to the last two bits of the preamble signal. Beginning at the instant t ₁ , precoded data is supplied to the recording unit 18 by the precoder 6.

During playback, a data stream schematically shown in Figure 4C is obtained. As can be seen in this figure, bits b _i-2 and b _i-1 are unknown bits. However, the reproduced data is effective starting from the time interval t ₁ . As a result, a sync word of full p-bit length can be used in the sync detector for sync detection during playback.

Figure 5 shows another solution to the problem. The apparatus shown in Fig. 5 is very similar to the apparatus of Fig. Thus, the elements of FIGS. 1, 2, and 5 having the same reference numerals are considered to be the same. 5, the switch 10 is integrated into the 2T precoder 6 'and the b- terminal of the switch 10 is further connected to the input 50 of the 2T delay unit 30 .

FIG. 6A again shows the preamble signal generated by the generator 12 at the instant t ₀ , t ₁ and the 2T precoded data supplied by the precoder 6 '. 6B shows the timing signal supplied to the switch 10 by the timing unit 22. Fig. As can be seen in the figure, the switch 10 is connected according to the b- terminal of the switch 10 is switched to the input of the instantaneous position in the t ab ₁ 2T delay unit 30, which is a delay unit (30 ), And as a result, the content of the delay unit 30 becomes equal to the last two bits of the preamble signal at the instant t ₁ of switching. As a result, the precoded data is supplied by the precoder 6 ', and the preamble signal is also accurately recorded.

Upon reproduction, the data stream shown in Fig. 6C is obtained. As can be seen in this figure, all bits recovered are valid. As a result, a sync word of full p-bit length can be used in the sync detector for sync detection during playback.

Fig. 7 shows another embodiment which is very similar to the embodiment of Fig. Under the influence of the timing signal 61 applied to the timing unit 22 ', a switch 60 is provided for multiplexing the preamble signal and the non-precoded data applied to the input 2. This generates the serial data stream shown in FIG. 8A. At instant t ₁ , the switch 60 switches between positions cb and ab. The coupling unit 32 of the 2T precoder as well as the terminal c of the switch 10 now receives the serial data stream of Fig. 8A. At instant t ₁ , switch 10 switches switch 10 from position cb to position ab under the influence of a control signal applied to input 24, as can be seen in Figure 8B. As a result, the signal shown in Fig. 8C is supplied to the input 16 of the recording unit 18.

Various modifications of the invention as described above are possible. In general, it has been described that an nT precoder (n is an integer satisfying n? 1) can be used. In the solution described in Figures 4A-4C, this means that the conversion to the switch position ab must occur at the instant t ₁ -nT.

4A to 4C, Fig. 5 and Figs. 6A to 6C, the effective part of the preamble signal after reproduction from the recording carrier is locked for the bit clock included in the preamble signal If sufficiently long to enable a person, in the transition to a momentary switch positioned to early point than t ₁ -nT ab is not any of the road exists.

It should be noted that, as shown in FIG. 2A, the preamble signal and precoded data can be recorded as the beginning of a track. However, it is also possible for a track to include several track portions located consecutively in the track. Each track portion includes a preamble signal followed by a precoded signal. The solutions described above will be applied to the generation of information to generate track portions in the track.

It should also be noted that the combination of the precoder and the switch may be integrated into one electronic device, such as an integrated circuit, or realized in software in a microprocessor.

The recording apparatus according to the present invention may be one of a helical scan recording type or a linear recording type. The invention is likewise applicable to a recording apparatus for recording on disc-shaped record carriers as well. The recording carrier may also be a magnetic recording carrier or an optical recording carrier.

Therefore, it should be noted that the present invention is not limited to the above-described embodiments but is limited only by the claims.

related document

(D1) EP-A 492,704 (PHN 13.546)

(D2) EP-A 317,013 (PHN 12.328)

Claims (9)

An apparatus for recording a digital information signal on a track on a record carrier, - input means for receiving said digital information signal, - encoding means for encoding the digital information signal to obtain a channel signal, the encoding means comprising an nT precoder, where n is an integer n > = 1, Bit time), said nT precoder comprises signal combining means and delay means for realizing a signal delay of nT, said encoding means, - preamble signal generating means for generating a preamble signal, Switching means for combining the preamble signal and the channel signal and having first and second input, output and control signal inputs, the first input of the switching means being connected to the output of the preamble signal generating means, Switching means, Timing means for timing the switching means such that the switching means supplies a channel-encoded block of information of the digital information signal following the preamble signal, - recording means for recording the channel encoded block of information of the preamble signal and the digital information signal in the track on the record carrier, the digital information signal recording apparatus comprising: Characterized in that the switching means forms the nT precoder section and the second input of the switching means is connected to the output of the signal combining means and the output of the switching means is connected to the input of the nT delay means , A digital information signal recording apparatus. The method according to claim 1, Wherein the timing means realizes an internal connection between the first input and the output during a time interval in which the preamble signal generating means generates temporal coincidence with at least a part of the time interval at which the preamble signal is generated, To supply a control signal to the control signal input of the switching means so that the switching means realizes an internal connection between the second input and the output during a time interval during which the information block is supplied to the input of the nT precoder for channel encoding And is adapted to the digital information signal. 3. The method of claim 2, Wherein the timing means is adapted to switch from the internal connection between the first input and the output to the second input and the output from the switching means at an instant mT (where m > 0) To switch to said internal connection between said control means and said switching means. The method of claim 3, and m = 0. An apparatus for recording a digital information signal on a track on a record carrier, - input means for receiving said digital information signal, - encoding means for encoding said digital information signal to obtain a channel signal, said encoding means comprising an nT precoder, where n is an integer n > = 1 and T is a bit time of said digital information signal, , the nT precoder comprises signal combining means and delay means for realizing the signal delay of nT, - preamble signal generating means for generating a preamble signal, Switching means for combining the preamble signal and the channel signal and having first and second input, output and control signal inputs, the first input of the switching means being connected to the output of the preamble signal generating means; Switching means, Timing means for timing the switching means such that the switching means supplies a channel-encoded block of information of the digital information signal following the preamble signal, - recording means for recording the channel encoded block of information of the preamble signal and the digital information signal in the track on the record carrier, the digital information signal recording apparatus comprising: The timing means realizes an internal connection between the first input and the output during the time interval in which the preamble signal generating means generates the preamble signal in a temporal coincidence with a part of the time interval, Wherein the switching means switches from the internal connection between the first input and the output to the internal connection between the second input and the output at an instant mT (where m > = 1) before the start of the supply of the information block, Means adapted to supply a control signal to said control signal input of said digital information signal recording means. 6. The method of claim 5, and m = n. 7. The method according to any one of claims 1 to 6, and n = 2. 9. An encoding device for encoding a digital information signal to obtain a channel signal, the encoding device comprising an nT precoder (where n is an integer n > = 1 and T is a bit time of the digital information signal) Wherein the precoder further comprises switching means having first and second input, output and control signal inputs, wherein the pre-coder comprises signal combining means and delay means for realizing a signal delay of nT, The second input being connected to the output of said signal combining means and the output of said switching means being connected to the input of said nT delay means. 9. The method of claim 8, wherein n = 2.

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